The Lisbon Treaty referendum is poised on a knife-edge today as the 'Yes' and 'No' camps pull out all the stops to get out their supporters -- while the rest of Europe looks on from the sidelines.

Slightly more than three million voters in this country will impact on the future of nearly 500 million people in 26 other member states across the European Union.

The political parties and campaign groups alike will unleash the biggest ever voter turnout drive for a referendum, with both predicting last night that the result will be tight.

The 'Yes' and 'No' camps finished off their campaigning yesterday with Taoiseach Brian Cowen canvassing in his heartland of Laois-Offaly, describing today's poll as "an important date in Irish history".

Polling stations will be open across the country from 7am to 10pm -- the longest period ever for a referendum.

Turnout is still expected to be under 50pc, with the 'Yes' side left hoping there won't be a repeat of the first Nice result, where the referendum was defeated. Observers remarked last night, however, on how extraordinary it was that a vote of such import will still prompt so relatively few to go out and vote. On the other hand, campaigners were saying the race had resulted in a heightened level of awareness, with much of the electorate taking an active view. The weather is expected to be good in most parts of the country, which would help to boost turnout.

Ireland is the only country to be holding a referendum on the European Reform Treaty, so the outcome here has the potential to sink the treaty or ensure its path is smoothed across the EU.

Party strategists are also keenly watching the difference between the turnout in Dublin versus the rest of the country.

And the 'Yes' campaign is particularly conscious that the first Nice Treaty referendum was lost because the pro-treaty vote didn't come out.

As in a general election, the parties will be transporting supporters to polling stations and monitoring the turnout.

Messages

Fianna Fail will put together what it regards as its biggest voter turnout campaign for a referendum and will be using text messages, phone calls and letters to ensure its supporters vote today. "The last 24 hours is the key period in any campaign. Each TD is appointed as director of elections so they are responsible for the activities in their area and putting out a 'get out the vote' strategy," a party source said.

Fine Gael distributed a special leaflet designed to encourage people to vote, as well as sending out text messages in the name of the party leader Enda Kenny.

"We're making a much bigger effort this time out," a spokesman said.

The 'No' campaigners will also be doing their best to ensure its supporters are out in force. Libertas is operating a telephone bank today to call people who identified themselves as 'No' voters when they were canvassed by volunteers to ensure they come out to vote.

Libertas will be focusing on voters in the city areas, especially Dublin. "That's where the real battle is on," a source said.

Mr Cowen claimed today's vote will decide whether Ireland continues its positive approach to the EU or begins a new and uncertain route.

He said that at a time of economic uncertainty, it is in Ireland's "vital national interest" to have a reformed European Union working for the country.

"After 35 years of respecting and helping Ireland, the EU has earned the right not to be seen as a threat to us and I believe that the Irish people will reflect on this when examining the arguments of both sides of the argument," he said.

Mr Cowen also said he did not believe the ongoing controversy over the personal finances of his predecessor, Bertie Ahern, was relevant to the referendum.

Merits

"People are looking at this issue on its merits and Mr Ahern is held in the highest regard by our organisation and we wish him well," he said.

Libertas chairman Declan Ganley has appealed to Irish people to turn out to vote and reject the treaty tomorrow, saying that a 'No' vote would "send our leaders back to the drawing board".

Fine Gael claimed many 'No' voters were switching to the pro-treaty side amid concerns about the negative fallout from defeating the Lisbon Treaty.

Fine Gael director of elections Gay Mitchell said he was "optimistic" of a 'Yes' victory. However, when asked if the treaty had been a "hard sell", Mr Mitchell conceded it had been difficult to make the pitch for a 'Yes' vote because there was no "one big idea" you could explain to voters.